Mechanical pencil of the push-out type



y 6, 1969 OSAMU TSUKAHARA 3,442,596

MECHANICAL PENCIL OF THE PUSH-OUT TYPE Filed March 15, 1966 Sheet of 2 FIG. 4

INVENTOR M4 TJIJKA/MWW y 1969 OSAMU TSUKAHARA 3,442,596

MECHANICAL PENCIL- OF THE PUSH-OUT TYPE Filed March 15, 1966 Sheet 2 of 2 United States Patent Oflice 3,442,596 Patented May 6, 1969 Japan Filed Mar. 15, 1966, Ser. No. 534,303 Claims priority, application Japan, June 29, 1965, 40/52,645 Int. Cl. B43k 21/22 US. Cl. 401-84 2 Claims ABSTRACT OF THE DISCLOSURE In a mechanical pencil of the push-out type, a lead retraction prevention member is provided which continuously supports the lead from its point of feed to the open end of the pencil.

In conventional ever-sharp pencils of the push-out type, the center bore of a front metal member has a diameter which is larger than the outer diameter of a lead, and an arcuate leaf spring is mounted on the inner surface thereof so that the lead, when pushed out, may not be retracted. A principal disadvantage of this arrangement lies in the fact that it is difficult to bring the lead, which is urged by said spring, into alignment with the center bore of a front metal member in the axial direction, the lead being liable to be deflected and broken. When the lead is broken in a space in front of a chuck, a broken piece of lead in the center bore is slightly deviated from the center at its trailing end as it is subjected to the force of the leaf spring, so that the leading end of the lead, when pushed by the chuck, is brought out of alignment with the trailing end of said broken piece of lead. If this occurs, the lead will become stuck in the center bore, thereby putting the pencil out of service.

It is an object of this invention to provide an eversharp pencil of the push-out type which has a lead retraction prevention member in the form of a cylinder having a plurality of longitudinal slits, said lead retraction prevention member being firmly mounted in a space between the center bore of a front metal member and the front end of a chuck. The center bore of said lead retraction prevention member and the center bore of said front metal member have a diameter which is substantially identical with the outer diameter of the lead so that the lead cannot be deflected in the bores even if it is broke. A broken piece of lead is not deflected but positively pushed out by the other broken piece of lead pushed by the chuck, thereby preventing the lead from becoming stuck in the pencil.

One embodiment of the invention will now be explained with reference to the drawings wherein:

FIG. 1 is a sectional elevation of one embodiment of this invention with the main body and the front metal member being out away to show the interior;

FIG. 2 is an exploded elevation of said front metal member;

FIG. 3 is an enlarged sectional elevation along the line AA of FIG. 1;

FIG. 4 is a view similar to FIG. 3 and showing an ever-sharp pencil of the conventional type;

FIG. 5 is an exploded sectional elevation of the pushdown portion of the embodiment shown in FIG. 1;

FIG. 6 is an enlarged fragmentary sectional elevation of another embodiment of the push-down portion, shown with a cap mounted thereon; and

FIG. 7 is an enlarged fragmentary sectional front elevation of the embodiment illustrated in FIG. 6, shown with a cap being removed.

The ever-sharp pencil illustrated in the drawings comprises a main body 1 having a lead cylinder 2 inserted therein. Threadably and integrally mounted on the lower end of the lead cylinder 2 is a chuck 4 for gripping and holding a lead, said chuck 4 being urged upwardly by a spring 5. A spring rest 6 is threadably mounted in the lower end of the main body, and an annular ring 8 which abuts against an offset portion formed on the front inner surface of said spring rest 6 bears against the chuck 4 which is urged upwardly by the spring 5, so that a lead is gripped and held by the chuck 4.

An ever-sharp pencil of the push-out type described hereinabove is known in the prior art. According to this invention, the portion of the spring rest 6 which projects out of the main body is externally threaded at 9 and is threadably received in an internally threaded rear opening 11 of a lead retraction prevention member .10. The aforementioned annular ring 8 is operatively brought into contact with the floor surface 12 thereof. There is formed in the center of said floor surface a recess 13 which is adapted to receive therein the chuck 4, said recess 13 having a center bore 15 adapted to receive the lead 14 therein. A cylindrical body 16 is made resilient by virtue of a plurality of longitudinal slits 17 formed therein. The front=end of said cylindrical body 16 yieldingly bears against the lead 14 by proper force of resilience.

A front metal member 19 has an opening whose internally threaded rear portion 20 threadably receives therein externally threaded center portion 18 ofthe lead retraction prevention member 10. The intermediate portion 21 of said opening snugly receives therein the cylindrical body'16 of lead retraction member 10. The center bore 22 formed in the front end of said front metal member 19 is in alignment with the center bore 15 of the cylindrical body 16 in the axial direction.

Referring to FIG. 5, the inner surface of the upper end of the main body 1 is threaded at 23 and threadably receives therein the lower end of a cylindrical holder 24 having an externally threaded portion 25. A cap 26 for the lead cylinder 2 has a front offset portion 27 which abuts against the upper end of the lead cylinder 2, and is provided with a rear offset portion 29 which abuts against an internal ofiset portion 30 of the cylindrical holder 24. It will be appreciated from the foregoing description that the cap 26 never slips off its position unless the cylindrical holder 24 is removed, so that the cap will never become lost.

In operation, pressing down the cap 26 brings the annular ring 8 into contact with the floor surface 12, and only the chuck 4 enters the recess 13 together with the lead 14. The chuck 4, when released from its engagement with the annular ring 8, spreads apart, so that the lead stops in its forward movement. Releasing a finger from the. cap 26 enables the chuck 4 to be restored to its upper position by the biasing force of the spring 5, but the lead is prevented from moving backwardly :by the lead retraction prevention member 10. When the chuck 4 is restored to its original position, it is pressed on its outer circumferential surface by the annular ring -8 and firmly grips and holds the lead 14. Thus, the present invention makes it possible to bring the chuck 4, the lead retraction prevention member 10 and the front metal member 19 into alignment with one another in the axial direction, so that the lead pushed out the chuck 4 is introduced into the center bore 15 of the lead retraction prevention member 10 without being deflected, and thence into the center bore 22. of the front metal member 19. The lead 14 is held so intimately in the bore that the impact of the pencil dropping from a height of several feet onto the ground will not cause the lead to be broken within the pencil. Even if the lead 14 is broken within the pencil by a 3 great impact, broken pieces of lead will be pushed out by the lead pushed by the chuck 4, thereby preventing the broken pieces of lead from becoming stuck within the pencil.

The arrangement shown in FIGS. 6 and 7 may be used to prevent the cap from being dislodged from its position on the upper end of the lead cylinder. The upper end of the main body 1 is internally threaded at 31, and a projection 32 formed on the outer circumferential surface of the front end of a cap 3 is adapted to threadably engage said threaded portion 31. In inserting a lead, the cap 3 is rotated to the left to release the projection 32 from its engagement with the threaded portion 31 of the main body so that the cap 3 may be removed. When the cap 3 is in the condition shown in FIG. 7, it is impossible for the cap 3 to push the lead cylinder in the main body even if the cap is pushed down by a finger, for the projection 32 abuts against the outer end of the threaded portion 31. Turning the cap 3 to the right to bring the projection 32 into a position inwardly of the threaded portion 31 of the main body 1 as shown in FIG. 6 enables the cap 3 to freely move upwardly and downwardly. Moreover, the cap 3 never slips off its position because the projection 32 abuts against the inner end of the threaded portion 31 of the main body 1.

While a preferred embodiment of the invention has been described and illustrated, it is to be understood that the invention is not limited to its precise form, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed as novel is:

1. In a mechanical pencil of the push-out type including a cylindrical main body open at both ends, a lead carrying cylinder centrally and slidably positioned within the main body, a chuck for gripping the lead carried in the lead carrying cylinder, said chuck being threadedly mounted in the forward end portion of the lead carrying cylinder and having its longitudinal bore in alignment with that of the lead carrying cylinder, the free end portion of the chuck being resilient, chuck closing means mounted on the end of the main body contiguous to said chuck, said chuck closing means being adapted to engage the resilient portion of the chuck and effect lead feeding upon relative movement of the chuck closing means and the resilient chuck portion, wherein the improvement comprises a lead retraction prevention member stationarily mounted on the main body outwardly of the chuck, said lead retraction prevention member having a longitudinal axial bore aligned with that of the chuck and being sized to closely surround and support the lead passing therethrough throughout the entire length of said bore, the length of the axial bore being such that upon maximum movement of the chuck in the direction of the aforesaid member there is virtually no clearance therebetween and said member having a resilient portion along the length of the bore to frictionally engage the lead and prevent retraction thereof.

2. The invention as described in claim 1 and wherein there is a front member fixedly secured to the lead retraction prevention member, said front member having an axial bore aligned with that of the lead retraction prevention member, said front member bore being sized to surround and support the lead passing therethrough whereby the lead is continuously supported throughout its travel through the lead retraction prevention member and the front member.

References Cited UNITED STATES PATENTS 2,473,149 6/1949 Juelss 401- 1,373,278 3/1921 Vierling et a1 401-67 X 1,846,604 2/1932 Maloney 401-67 2,484,640 10/ 1949 Mustard 40 I67 FOREIGN PATENTS 1,066,103 9/1959 Germany.

LAWRENCE CHARLES, Primary Examiner. 

